Machine for grinding helical gears and other conjugate helicoidal members



June 4, 1946. l. J. GRUENBERG 2,401,561

MACHINE FOR GRINDING HELICAL GEARS AND OTHER CONJUGATE HELIGOIDAL MEMBERS Filed Nov. 13, 1943 4 Sheets-Sheet l INVENTOR.

IVOR J.GRUENBEIRG -FIG.4.

ATTORNEYS I. J. GRUE NBERG 2,401,561 MACHINE FOR GRINDING HELICAL GEARS AND OTHER CONJUGATE HELICOIDAL MEMBERS Filed- Nov. 13, 1943 V 4 Sheets-Sheet2 'June 4, 19.46.

N ATTORNEYS "June 1946- l. J. GRUENBERG 2,401,

MACHINE FOR GRINDING HELICAL GEARS AND OTHER CONJUGAIE HELICOIDAL MEMBERS Filed Nov. .15, 1943 4 Sheets-Sheet 5 INVENTOR. IVOR J. GRUENBERG ATTORNEYS Jung], 1946.

, I. J. GRUENBERG MACHINE FOR GRINDING HELICAL GEARS AND OTHER CONJUGATE HELICOIDAL MEMBERS .Filed Nov. 13, 1945 4 SheetsSheet 4 INVF'VTOR.

IVOR J. GRUENBERG ATTORNEYS Patented June 4, 1946 MACHINE FOR GRINDING HELICAL GEARS AND MEMBERS OTHER CONJUGATE HELICOIDAL Ivor J. Gruenberg, Pleasant Ridge, Mich., assignor to The Gear Grinding Machine Company, Hamtramck, Mich., a corporation of Michigan Application November 13, 1943, Serial No. 510,169

3 Claims.

This invention relates to the grinding of helical gears and the like, and it is the object of the invention to obtain 7 a construction which is adapted not only for the grinding of the work but also for generating and maintaining a form in the grinder wheel which will grind the helicoidal surfaces to a predetermined cross sectional contour. To this end the invention consists in the construction as hereinafter set forth.

In the drawings:

Fig. 1 is a side elevation of my improved grinding machine;

Fig. 2 is an end elevation thereof;

Fig. 3 is a longitudinal section through the head stock of the machine;

Fig. 4 is a plan view of the means for rotating the work during its axial movement;

Fig. 5 is a cross section partly in elevation showing the grinder wheel and the mounting therefor;

Fig. 6 is a side elevation of Fig. 5;

Fig. 7 is a front elevation partly 'in section of a portion of Fig. 1, and

Fig. 8 is an enlarged elevation partly broken away of aportion of Fig. 2.

Generally described, my improved grinding machine comprises a reciprocatory carriage or work holding table, a rotary work holder mounted thereon, means; for rotating said work holder during and correspondingto the axial movement thereof to impart a predetermined helical movement to the Work, and a grinder wheel angularly adjustable into a plane generally corresponding to the helical angle of the work with respect to the axis of rotation thereof; The machine is also adapted to receive a trimmingmechanism which is mounted in the work holder or in axial alignment therewith to be moved through an exactly similar helical path. The detailed construction of this trimming mechanism is not the subject matter of this application, but in general it includes means for constraining a diamond or trimming cutter to a movement in a. plane through a path exactly corresponding to a predetermined cross sectional contour of the helicoidal surface. In addition the helical movement imparted to this trimming mechanism together with the movement in a plane as just described will generate a form in the grinder wheel for grinding a desired cross sectional contour. It is very important that this fashioning of the grinder wheel should be performed in the same machine and by the same movements imparted to the work, for this insures a Very high degree of accuracy. One reason for this is that any slight deflection due tolack'of absolute rigidity in the supporting frame will be the same for the trimming mechanism as for the work so that an error in the one would be compensated for in the other. a i

i More in detail, A is a suitable base on which is mounted a work table B slidable in ways C and reciprocated by suitable means (not shown) D is a head stock mounted on the table B and provided with a rotary hollow spindle E containing an inner spindle F carrying a center F. 1 There is rotatable adjustment shank G. of a bifurcated grinder wheel carrier G The upper end of the slide and bracket forms a shelf G supporting a table G on which is mounted an electric motor G The table G is secured to the upper end of' the shank G to rotate therewith and aheaded clamping screw G engaging a segmental slot in the shelf forms the means for holding the table, shank and grinder wheel carrier in any desired position of angular adjustment. The axis of the shank Gr intersects the axis of the Work holder so that the grinder wheel will be centralized above the work. G is the grinder wheel mounted on an arbor G journalled in the furcations of the carrier G A pulley G12 on this arbor is in alignment with the pulley G on the shaft of the motor G and has a belt driving connection therewith. Thus; the grinder wheel may be adjusted angularly to any position without disturbing its driving mechanism. For vertically adjusting the grinder wheel with respect to the work, a vertical shaft G journalled in the column G has a 7 threaded portion engaging a nut Gr on the slide G, and an operating handle G on a horizontal shaft G connected by bevelled gear wheels G with the shaft G serves to rotate said shafts and to thereby raise or lower the slide.

For maintaining operative relation between the work and. the grinder wheel during the grinding of the helicoidal surfaces, it is necessary that the work should rotate simultaneously with its axial advancement and in a ratio thereto to produce a helix of the desired helical angle. For this purpose the hollow spindle E, ha formed thereon a pinion E which is in mesh with the gear wheel E on a shaft E parallel to the spind e and beneath the same. On the shaft E is a pinion E which is in mesh with a rack bar E slidable in bearings E in the head tock to extend transversely thereof. The outer end portion of the rack bar E extends over a stationary shelf E supported by a bracket E from the .base A. On this shelf is longitudinally slidably supported a table E which is adjusted in position by a threaded shaft E on the shelf engaging a nut E depending from the table, while a hand wheel E forms a means of rotating the .shaft. E is a bar centrally pivotally mounted at E on the table E so a to be adjustable'into difierent angular positions thereon. Headed bolts E extending through said bar in the opposite end portions thereof and engaging inverted T-shaped segmental slots E in the table E serve to rigidly clamp the bar in position. The

. anism just described place the required reverse rack ba E has a roller bearing or shoe E se-f' tate the latter therewith. During'the rearward movement of the table B'a reverse rotation is imparted to the spindle and work by means here'- after described;

I ndeactng. mechanism Helical gears or other helicoidal member to be ground must be rotatively adjusted to bring the successive teeth'or helical surfaces in operative registrationwith the formed grinder wheel. For this, I have provided an' indexing mechanism which periodically rotatively advances the inner spindle F with respect to the hollow spindle E. As hown, the hollow spindle E has an exchangeable peripherally notched index plate H mounted thereon being detachably secured to a hub H keyed to said spindle. The inner spindle F has mounted on its rear end an arm H which atits outer end has pivotally connected thereto at H a dog H having a wedge-shaped detent H for engaging one of the notches in the periphery of the plate H. By disengaging the detent from the notch and rotating the arm H until said detent comes in registration with another notch which is re-engaged by the detent, the inner spindle F will be rotatably advanced a predetermined amount with respect to the outer hollow spindle E.

M can for preventing backlash In all gear train having a plurality of elements there is inevitably a certain amount of backlash. Thus, if the spindle F is alternately rotated in reverse directions through the mechanism above described, the backlash in the mechanism would change the position of the work with respect to the grinder wheel during the rearward movement from that which it sustains during the forward movement. Such effect I have prevented by maintaining a constant torque on the rotary spindle E which is acting in the reverse direction from the movement imparted through the mechanism actuated by the bar E Two forms of torque producing means are illustrated. In one, a pulley I on the hollow spindle E has a cable I thereon which extends upward and around a pulley I and thence downward being connected at its free end to a counterweight I The tension thus produced will take up all backlash in the mechanism between the bar E and the spindle E, and will also constitute an actuating means for rotating the spindle in the opposite direction.

The second backlash take-up means comprises va gear wheel J in mesh with the pinion E and mounted on a shaft J parallel to the spindle E. On this shaft is a' pinion J which engages a rack J on a piston J which engages a hydraulic cylinder J Fluid supplied to this cylinder at a predetermined pressure will, through the mechtorque on the spindle E.

. Operation As above described, it is a practical necessity to trim the grinder wheel to the desired contour, while it is in position in the grinding machine in which 'it subsequently performs its work. However, the construction of this trimming mechanism forms the subject matter of aseparate application for patent and will not be specifically described herein. It is only necessary to state that the trimming mechanism may: be exchanged for the work' in the work holder so as to have the same helical movement imparted thereto when thetable is advanced. During such advancement the trimming cutter is manually oscillated through the path to which it is constrained which will generate the proper form in the grinder wheel. Thi form changes as the grinder wheel wears and is retrimmed for the radius of the wheel is a factor in determining the form. However, the cross sectional contour ground in the work will be the same regardless of such changes in the wheel. 5

Assuming that the grinder wheel has been adjusted to the proper angle with respect tothe general helical angle of the surfaces to be ground and that said wheel has been trimmed to the desired form, the operation is as follows. I The work is engaged with the centers F; F and dogged to the head F so as to bring one of the helical surfaces to be ground inoperative relation to the grinder wheel. To engage the grinder wheel with said surface, it may be necessary to roll the work (or the trimming mechanism) into initial engagement with the grinder wheel while the table B is stationary. This may be accomplished by turning the hand wheel E and through the threaded shaft E and nut E moving the table E longitudinally on the shelf E". {The grinder wheel may then be lowered into engagementwith the work. Reciprocatory movement is neXt im parted to the table B which during its advancement in one direction will move the rolleror shoe E along the camming face of the bar E there by actuating said rack bar'in a direction transverse to the table and through the mechanism described imparting a corresponding rotary novement to the spindle F and the work connected therewith. This movement is such as to maintain the grinder wheel in operative relation to the helical surface at all points, in the axial advancement of the work. Upon reversal in movement of the table B, the grinder wheel will still be maintained in operative relation to the surface being ground as all backlash is taken up and the counteract: ing torque either from the cable or by the hydraulic means will cause the roller E to remain in close contact with the bar E This grinding action may be continued with downward adjustment from time to time of the grinder wheel until the exact form in the work is obtained. The indexing mechanism is then operated to advance the work to another helical surface and the operation repeated.

What I claim as my invention is:

1. In a machine for grinding helical gears and the like, the combination of a frame and a reciprocatory table mounted thereon, a rotary work holdermounted on said table, a rotary grinder wheel mounted on said frame in operative relation to the work in said holder, means operated by the reciprocation of said table for correspondingly rotating said work holder in opposite directions, and hydraulic pressure means for maintaining a. constant and uniform opposing torque on said work holder to take up all backlash in the rotating means therefor so as to maintain substantially the same path of movement relative to said grinder Wheel in both directions of reciprocation.

2. In a machine for grinding helical gears and the like, a frame, a reciprocatory Work table mounted on said frame, a rotary holder mounted on said table, a grinder wheel mounted on said frame above said work holder and in operative relation to the work therein, means actuated by and during the reciprocation of said table for correspondingly rotating said work holder in opposite directions, said means comprising a rack slidable transversely of said table, a gear train between said rack and work holder, a bracket on said frame, a table mounted on said bracket, a bar pivotally mounted on said bracket table to be adjustable into different angular positions with respect to the direction of movement of said work table, means on said rack travellingly engageable with said bar to be actuated thereby during the reciprocation of said work table, and means for adjusting said bracket table to temporarily withdraw said bar and facilitate the engagement of said grinder wheel with the work.

3. In a machine for grinding helical gears and the like, a frame, a reciprocatory table mounted thereon, a rotary work holder mounted on said table, a grinder wheel mounted on said frame above said table and work holder and adjustable into operative relation to the work, means actuated by the reciprocation of said table for correspondingly rotating said work holder in opposite directions, said means comprising a rack bar slidable transversely of said table, a transmission gearing between said rack bar and work holder, a bar mounted on said frame to extend obliquely in relation to the direction of reciprocation of said table, a roller on said rack engaging said bar to be actuated thereby in one direction during the movement of said table and to communicate a corresponding rotation to said work holder, and hydraulic pressure means for maintaining a constant and uniform reverse torque on said work holder to return the same during the reverse direction of movement of said table and to take up all backlash in said gearing.

IVOR J. GRUENBERG. 

